package main

import (
	"fmt"
	"strings"
)

func main() {
	var (
		n     rune = 0
		input string
	)
	fmt.Scanln(&n)
	fmt.Scanln(&input)
	ans := strings.Map(func(r rune) rune {
		return ((r-'a')+n)%26 + 'a'
	}, input)
	fmt.Printf(ans)
}
